1. Field of the Invention
The present invention generally relates to an image processing device, and more particularly, to an image processing device having a security function in a printing apparatus, such as a printer, a copying machine, or a facsimile, or in an input apparatus, such as a scanner, which stores obtained image data in the apparatus itself.
2. Description of the Related Art
Recently, recording media, such as a DRAM (Dynamic Random Access Memory) and a HDD (Hard Disk Drive) have become less costly; accordingly, it has become possible to store a large quantity of image data in an image processing device at a low cost. Thus, a storing (filing) function can be added to an apparatus which conventionally has only a function of printing on a sheet, or printing image data read from a subject document. Since an apparatus having the storing function is capable of storing image data that have been processed before, the apparatus can perform a reprocessing (i.e., outputting a same image data again) in a largely shortened operation time.
Whereas such apparatuses have become more convenient as above, there has occurred a security problem. Specifically, there has occurred a risk that a third person may illegally output the stored image data. Conventionally, a personal identification using a password has been introduced in an attempt to prevent such an illegal output.
By the way, though not aimed at preventing an illegal output of stored image, Japanese Laid-Open Patent Application No. 6-268791 describes a digital copying apparatus that can perform a normal copying process, and at the same time, can display image data on a monitor, for the purpose of tracking an illegal use of the apparatus. Additionally, Japanese Laid-Open Patent Application No. 7-212602 describes a copying apparatus having a security function which attempts to prevent an illegal use by converting image data into image data suitable for a reductive printing, and storing the image data. Thus, monitoring stored image data, or applying a predetermined process to image data upon storing the image data, is intended to enable a conjecture of the presence of an illegal use, or a conjecture of an illegal user.
However, regarding the above-mentioned conventional apparatuses, once the password for the personal identification is broken, it becomes difficult to conjecture whether or not there has been an illegal output, or who has output image data illegally. In addition, the digital copying apparatus and the copying apparatus having the security function described in Japanese Laid-Open Patent Application No. 6-268791 and Japanese Laid-Open Patent Application No. 7-212602, respectively, are aimed at preventing an illegal deed concerning a first output upon storing image data, and thus cannot deal with an illegal output of already stored image data (a second output onward). Further, those copying apparatuses are not contrived to facilitate a reprocessing using the stored image data.